In certain instances, office work productivity has significantly increased through advances in technology. Some of these advances in technology involve replacing paper documents in the workplace with electronic documents. One such advance provides office workers with the ability to send/receive and share documents electronically. Traditionally, many paper documents contain signatures to show authorship or indicate approval. Accordingly, it is also desirable to include signatures in the electronic documents, particularly when they are sent back and forth. As would understood, the inclusion of signatures in the electronic documents is easily achieved using graphic tablets, for example, which are computer peripheral devices for capturing handwritten data.
Once a signature is affixed to a document, people generally assume that the signature on a paper or electronic document is proof of authorship or approval. There is no guarantee, however, that the integrity of the signature, especially electronic ones, has not been compromised, for example, by being traced or otherwise forged. Generally, signatures on paper or electronic documents are vulnerable to two forms of deception. The first form of deception involves an invalid signature. An invalid signature is a signature created by a forger attempting to imitate the signature of another person, i.e., authorized signator. Such a signature is affixed on a document not authored or approved by the authorized signator. The second form of deception involves affixing a valid signature, which is a signature actually created by the authorized signator, on a document other than the original intended document. This form of deception, referred to herein as an invalid copy, is particularly difficult to detect when the signature has been "cut" from one electronic document and "pasted" onto a second electronic document since it looks exactly like the original signature.
For the aforementioned reasons, a number of people have reservations about allowing their signature to be captured electronically. Accordingly, there exists a need for protecting the integrity of a signature on an electronic document.